Electric switches



April 7, 1959 N. B. ERICKSON 2,881,293

ELECTRIC SWITCHES Filed Sept. l2, 1958 A TTORNEY United States Patent ELECTRIC SWITCHES Norman B. Erickson, Des Plaines, Ill., assignor to The Lfogrey Organ Company, Chicago, 111., a corporation 0 linois Application September 12, 1958, Serial No. 760,676

10 Claims. (Cl. 200-166) This invention relates to electric switches and operating mechanism therefor, and has particular reference to switches employing pressure responsive means enabling close circuiting the switch against the normal urge of means tending constantly to maintain the switch in open circuit.

Certain of the more essential objects of the invention are:

(l) The provision of a switch which is noiseless in operation.

(2) The provision of a switch, the circuit making an breaking elements of which are self cleaning.

(3) The provision of a switch which can be economically manufactured and consists of only a few coactive elements mounted and constructed so as not to be afiected by fatigue.

(4) The provision of a switch embodying a laterally movable resilient contactor, one end of which is attached to a fixed point by unique means in a manner to insure a good electrical connection to a voltage supply source and enable practically innumerable individual actuations thereof with avoidance of crystallization of the metal incident to frequent speedy fiexure of the contactor first in one and then in an opposite direction at said fixed point when engaging same with one and then the other of coactive contact elements.

(5) The provision of a system of retractile springs of relatively different traction characteristics, and means for mounting said springs and correlating same to respective contact elements so that one of the springs constantly urges the other spring into effective engagement with one of said elements, and whereby said one spring is coactive with a pressure responsive means to maintain the latter in a condition for operation by a tiltable element to move said one spring off of one and onto the other contact element.

(6) The provision of a switch having a longitudinally and laterally movable voltage conductor in the form of a first retractile spring and means consisting of a second retractile spring which constantly resists retraction of the first spring, said springs being interconnected to provide a unitary structure which may be easily attached to a mounting and arranged so as to resist retraction of the first spring and-to be connected to a voltage supply source and operatively correlated to spaced apart elements for engaging first one and .then the other thereof in lateral motion of the conductor.

The above and further objects of the invention will be more readily understood by the following description of one embodiment thereof, this being a specific adaptation for use With an electronic. musical instrument operated by a keyboard.

It shall be understood that the form of the invention described below represents only one adaptation of this invention which is-understood to include all variations conceivable within the scopeof the annexed claims and to those familiar with the art.

2,881,293 Patented Apr. 7, 1 959 Reference is made to the accompanying drawings wherein Figures 1 and 2 are schematic views respectively illustrating two different operated conditions of the switch. Figure 3 is a view in elevation of the switch on an enlarged scale, the same showing in full lines the condition of the switch as shown at Figure l and in dotted lines, the condition thereof as shown at Figure 2.

Figure 4 is a sectional elevation of a portion of the switch showing the conductor (first retractile spring) when pulledv on by. the second retractile spring and en gaged with the first contact element.

Figure 5 is a view similar to Figure 4 showing said first; retractile spring as when pulled an by the second retractile spring so as to move same 01f of the first contact element and onto the second contact elements.

Figure 6 is a detail sectional view through the first and second retractile springs showing their telescopic connection with each other and the means for preventing separation of the springs from each other during respective conditions of the springs occurring during operation l thereof.

Figure 7 is a detail view showing the means for detachably securing onevend of the second retractile spring to the mounting means.-

Figure 8 is a sectional view through a portion of the Y mounting means showing the means for attaching the conductor (first spring) to the eyelet and associated terminal clip on' the mounting means, and

Figure9 is a section on line 9--9 of Figure 8, before soldering said first retractile spring to said clip and said terminal clip.

In carrying the invention into practice, reference is first made to the schematic illustrations Figures 1 and 2 wherein X and Y are respective fixed points; A, a first contact element, B .and C secondcontact elements; R, a rocker arm pivoted at R'to swing clockwise and counterclockwise respectively, and provided at its outer end with spring attaching. means Z. .81 is a first retractile spring having one end attached to fixed point X. S2 is a second retractile spring having one end attached to fixed point Y. The opposite ends of the springs are attached to said means Z on rocker arm R. The tractional force of spring S2 is suflicientlygreater than that of spring S1 to constantly urge arm R to assume the full line position shown at Figure 1 and move spring S1 laterally to the right and engage same with contact element A. Thus, under the inherent force of-springzSZ, spring S1 is pulled longitudinally and moved laterally to effectively engage element A. When arm R is vtilted to approximately the dotted line position shownat Figure 1, spring S2 is partially stretched and spring S1 partially retracted and the latter engaged with element B.

Upon referring to Figure 2, arm R has been tilted counterclockwise an angular distance greater than that shown by the dotted line position, Figure 1, thereby further stretching and thereby tensioning spring S2 and exerting a downward and leftward pull on spring S1 and engagement thereof with contact element C, immediately following engagement of the spring with contact B. Both springs S1 and S2 are now in further stretched conditions with spring S1 firmlyandvery effectively engaged with said elements B and C.

Referring now to Figure 3 showing an organized switch assembly, M is a mounting means of hard flat insulating material such as a longitudinal strip presenting parallel upper and lower edges 11 and 12. On this strip, similar switches may be mounted and suitably spaced apart from each other longitudinally. R corresponds to rocker arm R shown schematically at Figures 1 and 2, the same pivoted at R1 on said strip to tilt laterally about a horizontal axis.

Ann R is formed with a depending cam R3 whose vertical center is disposed to the right of said axis R1 enabling the cam to ride freely on the upper flat surface of a conventional elongated organ key or other well known musical instrument or mechanism with which the switch is adapted to function to make and break an electrical circuit when the key is depressed and pressure then released. Such keys are fulcrumed at a point between the front and back ends thereof and in the instant case, depression of the front end tilts the key vertically and raises the back end thereof with resultant operation of the cam to tilt R counterclockwise. The lowered full line position of the back end of the key is indicative of an Ofi condition of the switch, the raised dotted line position thereof being indicative of an On condition of the switch, thereby tilting arm R in said counterclockwise direction.

Rocker arm R is formed at one side thereof adjacent to the free end of the arm with spaced apart spring retainer lugs R4R4 for the reception of the circumferentially reduced or constricted portion S3 of coil retractile spring S2, the same corresponding to spring S2 shown at Figures 1 and 2, the lower end of the spring being attached to the mounting means M 'at a point to the right of the vertical center line of cam R3. Attachment of the spring to arm R is effected by forming strip M with a vertical notch N which opens onto edge 12 of said strip, the lower end of the spring having a terminal circumferentially enlarged portion 1 of greater internal and external diameters than the intermediate body portion of the spring. Enlargement 1 is structurally similar to enlargement 2 which is a continuation of the reduced portion S3 at the opposite end of said spring. Enlargement. 1 is confined in back of mounting means M as shown at Figure 7. This is accomplished by first slipping the lower end of the spring into the notch by an upward lifting thereof while the enlargement is positioned to come in back of said means and confined thereagainst. Enlargement 2 is coactive with lugs R4-R4 as shown at Figure 3, the reduced portion S3 being received between and the enlarged portion 2 confined against said lugs by the inherent tendency of the spring to retract. Under this action of the spring, rocker arm R is tilted clockwise and the effective camming surface of cam R3 resiliently advanced against the upper fiat surface of key K at the back end of the latter, thereby fiepressing said back end and raising the front end of said Terminal clip 4 is secured to mounting means M by a metal eyelet 5 which passes through said means to expose a substantial portion of the eyelet from one side of said means. As shown at Figures 8 and 9, said eyelet is bifurcated to provide spaced apart portions 5a5a for snugly receiving the upper end of spring S1 therebetween where it is adapted to be frictionally held and soldered to the eyelet and said terminal clip. A substantial length of the spring is shown attached to the eyelet enabling lateral flexure of the spring with avoidance of crystallization and possible resultant breakage of the wire, regardless of the speed at which the switch is operated.

As shown at Figure 6, spring S1 is smaller in diameter than spring S2 and is telescopically connected therewith. To prevent longitudinal separation of the springs from each other incident to stresses and forces applied thereto during operation of rocker arm R, circumferential enlargement 3 of spring S1 engages a juxtapositioned convolution 3a of spring S2 as clearly shown at Figure 6. Lugs R4-R4 are equivalent to point Z in Figures 1 and 2. Clip 4 is equivalent to fixed point X, and enlargement 1 of spring S2 and the mode of attaching the spring to means M are properly considered as point Y in Figures 1 and 2.

At Figure 4, spring S1 is being subjected to the force exerted thereon when moving arm R from the dotted to the full line position shown at Figure 3. In this actuation of said spring, the convolutions thereof are pulled across contact element A with'aneffective wiping action thereagainst. In like manner is there a wiping action between said convolutions and element A when stress is removed from spring S1 and the latter tends to retract.

At Figure 5, spring S1 has been moved ofi of contact element A and onto contact elements B and C, the former the first to be engaged by said spring. The wiping action between the spring and said elements is the same as described with engagement of the spring with and disengage ment thereof from element A. Element C is disposed slightly to the left of the vertical center line of element B, such that it is the first to be engaged by spring S1. Successive with this engagement, the spring is flexed to the left and underneath element C. This relationship to each other of said elements B and C insures close circuiting the switch even though only one of said elements is engaged by the spring. When used in an electric organ, terminal 4 is connected to a tone signal supply source so that spring 51 is a conductor adapted when engaged with either one or both elements B and C to enable transmission of signal voltage to the customary transducer in.

the output system of the instrument.

In practice, means M may contain any desired niunber of similar switches, spaced apart from each other longitudinally a distance enabling coaction between different keys of a conventional keyboard and correlated switches. While the invention is primarily designed for the purpose herein stated, this is not to be construed as a limitation upon use of the invention.

What I claim as my invention is:

1. An electric switch comprising mounting means of electrical insulating material; two telescopically connected coil retractile springs of relatively different traction strength, each spring having an outer end attached to said mounting means; first and second contact elements spaced apart from each other on said mounting means and between which elements, one of said springs passes and is adapted to be moved ofi' of one and onto the other of said elements, the points of attachment of the other ends of said springs to said mounting means being such that said one spring, supplemented by the energy applied thereto by the other spring tends always to engage said one spring with said first contact element; and actuating means movably mounted on said mounting means and connected to said other spring so that in one operation of said actuating means said other spring is stretched and said one spring moved off of the first and onto the second contact element with a wiping action between same.

2. An electric switch comprising a mounting means of electrical insulating material having a metallic terminal clip adapted to be connected to a signal voltage supply source; a split metal eyelet passing through said means and through said clip and attached thereto, said eyelet providing a contactor attaching receptacle; a laterally movable elongated contactor comprising a coil retractile spring having a number of its convolutions at one end of the spring received in and soldered to said receptacle; first and second spaced apart contact elements secured to said mounting means, said contactor spring freely extending through the space between said contact elements enabling engagement of the spring first with one and then the other of said elements; and means coactive with the opposite end of said spring functioning normally to stretch said spring ahd move same laterally into engagement with the first contact element and adapted selective- 1y to enable retraction of the spring and move same laterally in an opposite direction and engage same with said second contact element.

3. In an electric switch, mounting means of electrical insulating material having first and second spaced apart contact elements, said mounting means presenting parallel longitudinal edges, a terminal clip secured to said mounting means; an elongated contactor comprising a coil retractile spring having one of its ends soldered to said clip, said spring extending through the space between said contact elements and adapted to be moved off of one of said elements and onto the other thereof; a retractile spring of greater traction strength than said contactor spring, the same having one of its ends attached to the other end of said contactor spring and its opposite end to said mounting means at a point thereon so that said second springs tends constantly to pull upon said contactor spring and engage same with the first contact element; and means coactive with the second named spring for stretching same with resultant retraction of the contactor spring and movement thereof into engagement with the second contact element.

4. An electric switch comprising a flat strip of hard insulating material; a terminal clip secured to said strip; a contactor comprising an elongated coil retractile spring having one of its ends attached to said clip; a second elongated contractile spring of greater traction strength than said contactor spring, said second spring having one of its ends attached to said strip and its other end to the opposite end of said contactor spring; first and second spaced apart contact elements mounted on said strip with the contactor spring extending through the space between said elements enabling movement of the spring laterally with resultant disengagement thereof from one and engagement of same with the other element; the point of connection of the second spring with said strip being situated relative to the point of attachment of the contactor spring that the second spring tends always to spend its energy on the contactor spring and engage said contactor spring with the first contact element; and means coactive with the second named spring for actuating same with resultant lateral movement of the contactor spring toward and into engagement with the second contact element.

5. An electric switch comprising mounting means of electrical insulating material having first and second spaced apart contact elements; a contactor comprising an elongated retractile spring extending through the space between said elements enabling lateral motion of the spring from one of said elements to the other; a rocker arm supported by the mounting means; and a retractile spring of greater traction strength than the contactor spring, said second named spring having one of its ends attached to the mounting means and the other end thereof to the opposite end of the contactor spring and connected to said rocker arm so as constantly to pull on and tension said contacting spring and tilt the rocker arm with resultant engagement of said spring with the first contact element, said rocker arm having means responsive to pressure applied thereto for moving said rocker arm in a direction to tension the second spring and cause relaxation of the contactor 6 spring and engagement thereof with said second'contact element.

6. An electric switch comprising a strip of hard electrical insulating material having first and second spaced apart contact elements; a contactor comprising an elongated coil retractile spring attached at one of its ends to said strip; means tending constantly to pull on said spring to tension and engage same with the first contact element, said strip of insulating material having a notch at one end thereof, the aforementioned pulling means comprising a coil retractile spring of greater tractional strength than the first named spring and provided at one end with a portion received in said notch and detachably secured to said strip and having its opposite end connected to said first named spring for activating same as aforementioned; and means coactive with the second named spring for pulling thereon to tension same and allow retraction of the first named spring and engagement thereof with said second contact element.

7. An electric switch according to claim 6 wherein the last named means comprises a rocker arm supported by said strip of insulating material and connected to said second named spring for movement thereby in a direction corresponding to that of the first named spring when engaging the first contact element.

8. An electric switch according to claim 6 wherein the last named means has separable connection with said opposite end of the second named spring.

9. An electric switch comprising two spaced apart contact elements insulated and spaced apart from each other, first and second interconnected coil retractile springs, each having a fixed terminal, said first spring extending through the space between said contact elements, the second spring being of greater traction strength than and tending always to stretch the first spring and move it laterally in a direction to engage same with the first contact element, and an actuator coactive with said springs actuable to cause relaxation of succeeded by stretching the first spring and moving it laterally in an opposite direction and into engagement with the second contact element.

10. An electric switch according to claim 9, wherein upon moving the first spring laterally in an opposite direction and engaging same with the second contact element, the second spring is partially wrapped about said second contact element.

Evett Nov. 6, 1951 Larsen et a1. Mar. 3, 1953 

